Chain terminated polycarbonates



United States Patent 3,177,179 CHAIN TERMHNATED PULYCARBONATESLieng-huang Lee and Henno Keslrknla, Midland, Mich, assignors to The DowChemical Company, Midland, Mich., a corporation of Delaware No Drawing.Filed May 31, 1960, Ser. No. 32,575 9 Claims. (Cl. 260-47) Thisinvention relates to new and improved polycarbonate resins. Moreparticularly it relates to high molecular weight polycarbonate resinshaving improved properties especially with regard to thermal stabilityand ease of fabrication.

It is known that polycarbonate resins can be made which have exceptionalstrength and outstanding toughness. However, these resins are difiicultto fabricate from a melt thereof because they have very high viscositiesat temperatures slightly above their melting points. It has beensuggested that this difficulty can be overcome by fabricating highmolecular weight polycarbonate resins as temperatures substantiallyabove their melting points. When, however, a polycarbonate resin isheated to a temperature substantially above its melting point in orderto fabricate it at a lower viscosity the polymer degrades and theresultant products have considerably reduced values for strength,toughness, heat resistance, transparency and other desirable properties.

It is among the objects of this invention to'provide new and improvedpolycarbonate resins.

A further object of this invention is the provision of such polymerswhich can easily be fabricated from melts thereof into shaped articles.

A particular object of the present invention is the provision of highmolecular weight polycarbonate resins which are thermally stable andhave low melt viscosities.

Other objects and advantages of the present invention will be evident inthe following description.

It has now been discovered that high molecular weight polycarbonateresins having certain terminal groups on the polymer chains haveimproved properties, particularly low melt viscosity and high thermalstability. According to the present invention polycarbonate resinshaving terminal groups formed by the removal of hydroxyl hydrogen ormercapto hydrogen from certain hydrocarbon alcohols and mercaptans havelow viscosities at temperatures above their melting points and highthermal stability. The alcohols and mercaptans which form the chainterminators of this invention are mono-functional in the sense that theycontain only one group which is reactive with chloroformyloxy groups.They have only one hydroxyl or mercapto group and no other functionalgroup. The hydroxyl or mercapto group of the chain terminator of thisinvention is attached to an aliphatic carbon atom and not directly to anaromatic ring since it has been found that phenol and its derivativeswhen used as chain terminators do not produce resins having theproperties of the resins of the present invention. Chain terminatorssuitable for forming terminal groups of the present invention mayhowever have phcnyl substituents. According to the present invention,compounds suitable for use as chain terminators for producing highmolecular weight, thermally stable, polycarbonate resins having low meltviscosities are monofunctional, saturated aliphatic alcohols and thiolsincluding such alcohols and 3,177,179 Patented Apr. 6, 1965 ice thiolshaving aryl substituent-s and having a molecular weight of less than400. Representative examples of compounds suitable as chain terminatorsin accordance with the present invention are ethyl alcohol, isopropylalcohol, tertiary butyl alcohol, cyclohexanol,4,5,6,8-tetramethylnonanol, n-tridecyl alcohol, n-octadecyl alcohol,benzyl alcohol, alpha-phenylethyl alcohol, beta-phenylethyl alcohol,benzohydrol, triphenyl carbinol, omega-phenylpropyl alcohol and thecorresponding mercaptans. The chain terminators of the present inventionhave a structure corresponding to the formula RXH in which R is amonovalent hydrocarbon radical free of aliphatic unsaturation having itsvalence bond on an aliphatic carbon atom, and in which X is O or S.

The carbonate polymers of the present invention are represented by theformula W Y L J. in which -O-,-A--O- represents the divalent residuewhich can be obtained by the removal of hydroxyl hydrogcns from a diol,T represents the monovalent residue which can be obtained by the removalof reactive hydrogen from a chain terminator of the present inventionand n is an integer greater than 20 and preferably greater than 40.

The divalent residue can be obtained from a glycol such as ethyleneglycol, tetramethylene glycol, hexamethylene glycol,1,4-dihydroxycyclohexane, and decamethylene glycol.-Preferably,'however, the divalent residue O-AO is obtained fromcompounds represented by the formula HOArBAr'-OH and forming polymersrepresented by the formula L Ar B Ar 0 CIn T in which A1- and Ar aredivalent benzene nuclei, that is, phenylene and substituted phenylene,and B is a divalent aliphatic or cycloaliphatic radical, oxygen orsulfonyl. Preferably, B is alkylidene or cycloalkylidene, that is, Arand Ar are joined to the same carbon atom of the B radical. Ar and ,Ar'are preferably linked into the polymer chain at the 1 and 4 positions,the 4 positions being linked to B and the 1 positions being linked tooxygen in the polymer chain. When Ar and Ar are further substituted, thesubstituents are preferably in the 2 and/or 6 positions. Illustrativeexamplesof the B portion of the polymer in the above formula when B isalkylidene are methylene, ethylidene, propylidene, isopropylidene,2,2-buty-lidene, 4-methyl-2,2-butylidene, and cyclohexylidene.Representative examples of Ar and Ar substituents are methyl, ethyl,isopropyl, Z-tertiarybutyl, phenyl and chloro.

The diol is preferably a diphenol, especially an alkylidene diphenol.Representative examples of alkylidene diphenols useable as a basematerial for making polycarbonate resins of this invention are4,4'-isopropylideneorthocresol, 4,4'-isopropylidenebis(2-phenylpheno1)and 4,4-isopropylidene-bis(2,6-dichlorophenol). Other diphenols such as4,4'-sulfoxyldiphenol and 4,4'-oxydiphen- 01 can be used in making thepolymers of this invention. The diol used to make the chain terminatedpolycarbonate resins of this invention can be a pure compound or mixtureof diols. T is'a monovalent radical formed by the reaction of a chainterminator of this invention with an end group, -When Ar and Ar are both1,4-phenylene, the polymer has recurring units corresponding to. the

structure and when in addition "B is isopropylidene, the polymer of thisinvention has'a structurecorresponding to the formula -in which T is aradical obtainedfrom the chain terminator.

Subscript n' is' an integer greater than 20 and preferably "greaterthan'40.

The -po'lymers of this invention can'be made by modifyin'g knowntechniques 'for making'polycarbonateresins such as by the phosgenation'of 'diols or {by the reaction of a diol' with a bischlorofor'matefuchmodification com- 'prising the addition-of a-'-'chain "terminator ofthis invention to the reaction mixture.

' The following examples -are'illustrative of the invention but theinvention is not limited thereto.

Y Example I T o a solution of 250 grams ofsodium hydroxide dissolved in3 1 liters "of water there are added-with stirring, 57-0. g1=ams of4,4'4sopropylidenediphenol and-2.5 liters of methylene chloride. Theresulting mixture is poured into "a lO' 'lite'rthremouthed flask. Theflask and con- --tents are placed in alconstant temperaturebath-maintained tents are stirred vigorously and phosgene gas is ledinto the flaisk-" below the surfacelof the liquid-through a sinte'redglass tube until endpoint-at a pH of 7' is reached.

7 *T pant ofthe ernulsiomthus' formed is added 2.5 m0l -'percent,f basedonfi -part' of the-4,4'-isopropylidenediphenol previously added, of amixture of primary tri- 'deeyl alcohols; the tridecyl alcoholsbeingpredominantly tetramethylnonanols. There is' the'naadded asolutioncontaining 75 milliliters of water, 9 grams of sodium hydroxideand .2 grams of 4,4'.-isopropylidenediphenol. Stirring is continued for1 hour and l milliliter of a 65 percent: aqueous solution ofbenzyltrimethylarnmonium chloride is thenaddedas.acatalyst. Theresultant emul-l sionis againstirred until it separates into two layers.The supernatant water-is decantedv and :rnost of the. methylene chlorideis then vol-atiliz'ed by heating the solution." The viscous mass thusobtained is put. on a glass plate, .air dried overnight and then further-dried-in a' vacuum oven ate-temperature of between l10 .C.-and 120 C.The product .is a dense white solid. A. melt-of athis polymer at 290- C.is transparent and remains colorless at 340 C. (Unsatisfactorypolycarbonate resins decompose or darken" considerably; at thesetemperatures.) This 1 chain terminated. polycarbonate resin has -a:.melt viscosity atv 310; C.- of 1295poises-obtainedusingthe-equipmentand technique-described by Karam et al.in A New Melt viscometer, -Modern Plastics,- volume 32, Number 7, March1955, at a shearing stressof 700,000 dynes per square centimeter. .This.polymer .has a K value of 63..

K is equal to 1,000k and k is calculated from the Fikfil'lt- --scherequation --wher'eirr N, is the viscosity' of asolution of the samplerelative toT-the viscosity of the: solventaand c is theconcentr'ationrof; the'sample in" the solution. Thesolv'entusedwirr-thistest is-ldioxane. "-Ihepolymer obtained in example hasexcellent thermal stability. Its viscosity decrease after being held a310 C. for, 30 minutes is very slight. r a 7 The above mentionedtridecyl alcohols are primary alcohols. There are no compounds presenttherein containing a quaternary carbon atom or substitution in the The:procedure of Examplel is repeated-usingjthe.-same materials andproportions except that 2.5 vrnol percent,

' based on the 4,4-isopropylidenediphenol as in'Example I, of tertiarybutyl alcohol issubstitutedfor tridecyl alcohol as the chain terminator.This tertiary butyl alcohol chain'terrninated polycarbonate resin has atransparent .melt at 290C. and a very light tint at-340- C. It has a 1Kvalue, obtained asin Example I, of 58,;and a melt viscosity at 3l0 C. of.1230. [This polymer hashigh thermal stability. The viscosity of thispolymer after 'being heldat -310- CrfOI 30 minutes is only'slightly lessthan the initial viscosity.

Example 111" To .a solution of 230 :grams offsodium hydroxide inir-litersof;waterv contained ,in; a reactor .are added with stirring,570 grams of 4,4'-isopropylidenediphenol and 2.5

. liters of methylene chloride. The resulting liquid-nr'xture ismaintained at a temperature of between 26 C. .and 27 I C. Themixture is'stirred' vigorouslyandphosgene gas is 40 5 below the liquid surfaceuntil the pH oftheliquid drops to fed into the-reactor througha sintered.glasstube situated 7. ;To 0.1 part of the emulsion thus formedare-added'l mol percent, based on 0.1 the amount'of4,4'.-isopropylivdenediphenol previously-added, of benzylymercaptan, 9.-grams of-sodium-hydroxide, and 75' milliliters of..water.

Stirring-is continued mechanically overnight. Thematerial separates intotwo layers. The supernatant water is decanted and methylene chloride. isthen'volatilizedby ,heating. The viscous mass thus obtained. is put on aglass. plate, air ,dried overnight and then further dried in a vacuumvoven at a temperature of between 110 .C. and 120 C. .The productiis. adensev white, high molecular weight, polycarbonate resin havingvexcellent thermal I stability and low melt viscosity. It can befabricated into.

' strong, tough films, filaments, and other shaped articles.

Examples IV 'through VI The procedure of Example. III is repeated usingthe same materials and proportions except that 2.5 mol percent based. onthe 4,4.-isopropylidenediphenol.as. in Example. IHof one of each ofthe-following materials is substituted for the benzyl mercaptanz.ExamplesIV, cyclohexanol; Example V, tertiary butyl mercaptam-Example'VI, beta-phenylethyl alcohol.

The products; .are high molecular weight polycarbonate resins ofoutstanding thermal stabilityand shaped articles can be made easily fromtheir melts by injection molding, extrusion, casting, and otherstandardtechniques.

Similar excellent results are obtained using other chain terminator-softhis inventionas above defined including those ,terminatorsspecifically denominated.

The chain terminated polycarbonate resins ofthe present invention arecharacterized by high molecular weight,

exceptional thermal stability and,.low .melt' viscosity.

. 'I hese resins are usually'transparent and range from colorless toslightly tinted. They can be mixed with dyes,

delusterants, pigments, plasticizers, reinforcing materials and withother polymers. They are easily fabricated into useful articles such asfilms, fibers, sheets, tubes, rods and the like from a melt or solutionthereof by conventional shaping techniques such as molding, casting, andextruding. The resins can also be used to make laminates, such as safetyglass and as protective or decorative coatings.

That which is claimed is:

1. A high molecular weight, thermally stable chain terminatedpolycarbonate resin having a structural in which -OA-O- is the divalentresidue of removal of hydroxyl hydrogens from a diol selected from thegroup consisting of glycols and diphenols, n is an integer greater than20, and T is the monovalent residue of removal of reactive hydrogen froma monofunctional chain terminator having molecular weight less than 400,reactive with chloroformyloxy groups, free of aliphatic unsaturation,and selected from the group consisting of alcohols and mercaptans.

2. A high molecular weight, thermally stable chain terminatedpolycarbonate resin according to claim 1 in which the chain terminatoris a tridecyl alcohol.

3. A high molecular weight, thermally stable chain terminatedpolycarbonate resin, according to claim 2 in which the chain terminatoris a tetramethyl nonanol.

4. A high molecular weight, thermally stable chain terminatedpolycarbonate resin according to claim 1 in which the chain terminatoris tertiary-butyl alcohol.

5. A chain terminated high molecular weight polycarbonate resin having astructural formula in which the hexagons represent benzene rings, B isselected from the group consisting of a divalent hydrocarbon radical,oxygen, and sulfonyl, n is an integer greater than 20, and T is themonovalent residue of removal of reactive hydrogen from a monofunctionalchain terminator having molecular weight less than 400, reactive withchloroformyloxy groups, free of aliphatic unsaturation, and selectedfrom the group consisting of alcohols and mercaptans.

6. A chain terminated polycarbonate resin according to claim 5 in whichthe chain terminator is a tridecyl alcohol.

7. A chain terminated polycarbonate resin according to claim 5 in whichthe chain terminator is a tetramethyl nonanol.

8. A chain terminated polycarbonate resin according to claim 5 in whichthe chain terminator is tertiary-butyl alcohol.

9. A chain terminated high molecular weight carbonate polymer having astructure given by the formula Hi0- .03]. LC 2%? i in which n is aninteger greater than 40 and T is a radical formed by the removal ofhydroxyl hydrogen from a material selected from the group consisting ofa tetramethyl nonanol and tertiary-butyl alcohol.

References Cited by the Examiner UNITED STATES PATENTS 1,921,756 8/ 33Kienle 260-77 2,889,312 6/59 Szayna 260-77 2,950,266 8/60 Goldblum260-47 2,970,131 1/61 Moyer et al. 260-47 3,028,365 4/62 Schnell 260-47OTHER REFERENCES Wagner et al.: Synthetic Organic Chemistry (1953), JohnWiley & Sons, Inc., New York (pp. 483-484 relied upon).

WILLIAM H. SHORT, Primary Examiner.

H. N. BURSTEIN, J. R. LIBERMAN, WILLIAM H.

SHORT, Examiners.

1. A HIGH MOLECULAR WEIGHT, THERMALLY STABLE CHAIN TERMINATEDPOLYCARBONATE RESIN HAVING A STRUCTURAL FORMULA